Electrical induction-furnace.



k K. A. F. HIORTH. ELECTRICAL INDUCTION FURNACE.

APPLICATION FILED 00T.8, 1913.

1,0993140, Patented June 9, mi I :ments in :i KARL ALBERT rnnnnrx 'Hron'rrr, or onnrsrrnmymnwny.

' ELECTRICAL 1 INDUCTIONFURNAGE.

Specification of' nette rs-Tat'ent.

natenteorune a; 4 914.

. Application filed October 8, 1913. Serial No. 794,026.

T9 all whom it may concern.-

. .Be it known that LKARL ALBERTFRED- RIK- Hron'rin, a subject ofthe King of Norway, residimqlat Christ-iania, Norway, have invented cer a in new and useful Improve- .e'ei rical- InductionFurnaces; and I do he e g'yQdeclare the following to be a full,-clear,-and exact description of the i nventiornsuch as will-enable others skilled in the art to which 'it 'appertains to make and use the same, reference being had to the ac- -companying drawings, -and to letters or --n1eans of which such furnaces are-made tion furnaces of the disk transformer figures 'offi u fornce marked-thereon, which form a p'ait of this specification.

This invention relates to electric inductyp andhas for its object an improvement by more suitable for metallurgical purposes.

In induction furnaces of the disk transformer type the bath is arranged around the iron core and between the co-axial primary coils in such manner, that the bath iswholly or partly covered by the upper primary cell. Therefore this latter must either inone manner or another be removed, when the a various metallurgical operations such as the slag treatmentthe-charging and the like is to take place or the metal bath must be pro vided with extensions, not covered by the upper primary coil.

According to the, presentinventionthe primary coil is arranged in such manner that the above mentioned drawbacks are avoided the bath being freely accessible. This is obtained by givin -the upper and the lower primary coil di rent diameters, one of the coilsh-aving a diameter greater than that of the meltingbath and the other coil having a smaller diameter than that of the bath, so that the annular center line of the bath is situated substantially on the conical surface through the center lines of the two coils and about straight between these latter. By this arrangement is obtained firstly that the'bath will be easily accessible so that operations, such as the'working of the slag supplementary addition of charge and the like could be carried out without the upper coil being lifted as is the case with known furnaces of this type and secondly the construction of the furnace becomes simpler and cheaper especially on account of the fact that there are no movable connections between the coils themselves or between the coils and the supply conduits.

the coil directly under the same timewthe great variationsflihload caused by lifting-and lowerin the coils, are

avoided. Further it is..also made' possible toarrangethebath much nearer to the lip-- per yoke of the cores sothat-the cores-'cou d be made shorter, this effecting asavin of iron and also an improvement in-thet e'renoe of phase mainly owing to the fact that the 1I0I1 is brought into the path 0f. the stray field of-:the coil .parts,"which are situated immediately belowthe yoke thereby -preventing. some. .lines of, power from straying.

Considered as a transformer the furnace is .in possession ofthe advantages'of the prior furnace of the upper and the lower coil on each (leg as a disktransformer type, the

whole-acting in substantially the same manner as two coils oft-he same diameter. as the bath! The coil therefore retains the character of a disk winding with divided coils.

The dynamical action of the two coils on the bath partly balance one another so that the inclination and the radial movement of the bath is no greaten than in the prior furnace.

i Experience shows, that the steel when The coils being; stationary the inductance'fof the furnace will alwaysbe consta'nt and. at

breaking through-the fireproof lining always takes its way inward to the magnet (along the line .70. y on thedrawing) and downward. Bythe present arrangement the lower coil will therefore be better protected against destruction when such breaking through occurs than in furnaces having the bath. As the upper coil may be moved. nearer to the bath the thick cover (about 100 mm.) being not interposed-cos (p will be as favorable as possible. By this arrangement the cooling of the upper coil will be more'eflicient than by coils above the cover.

An embodiment of the invention is diagrammatically illustrated in the accompanying drawing in connection with a furnace of the disk transformer type.

Figure 1 shows diagrammatically a verti Fig. 2 15 cal sectional'view of the furnace.

3 shows a plan view partly in section. Fig. a section along the line 3-3, Fig. 2.

In the example shown A is the iron core,. B the upper and C the lower primary coil D is the melting bath, comprising in known manner an annular channel surrounding each of the core legs, both being connected with a widened central bath. As will be seen each of the annular channels of the metal bath is arranged in such manner that an oblique line through the sectional surfaces of the two coils intersects the sectional surface of the melting bath. [at the top the melting bath is quite free and easily acces sible at every point. L is a cover for the annular channels containing the. melting bath. As the lower primary coils should not be so arranged as to intersect one another and as it is not advantageous to make the distance between the legs of the core too large the lower greater coils are somewhat flattened on the inside as shown in Fig. 2. Preferably about 5% of the circumference is made circular and concentrical with the upper coil, while 9,- of the circumference is flattened.

Claims.

1. In an electrical induction furnace, a magnetic core, a furnace having a channel embracing the core to provide for the melting bath, and two flat conductor coils embracing the core and lying in substantially parallel planes, one of said coils having an outer periphery less than the inner periphery of the channel, and the other of said coils having an outer periphery greater than the inner periphery of the channel, and one of said coils lying wholly below the plane of the top of the channel and the other of said coils lying wholly below the plane of the bottom of the channel; substantially as described.

2. In an electrical induction furnace, a magnetic core, a furnace having a channel embracing the'core to provide for the melting bath, and two conductor coils embracing the core, one of said coils lying near the plane of the top of the channel, and the other of the coils lying below the plane of the bottom of the channel, and the conductor parts of the two coils lying at different dis tances from the core so that an imaginary straight line through the centers of the conductor parts passes through the lower part of the channel; substantially as described.

3. In an electrical induction furnace, a magnetic yoke, a furnace having a channel with a central portion extending through the yoke and branches extending in opposite direction outside of the yoke to provide forthe melting bath, two conductor coils embracing individual sides of the yoke and lying near the plane of the top of the chan nel between the central portion and the branches of the channel, and two other'conductor coils embracing the individual sides of the core and lying wholly below the plane of the bottom of the channel, the conductor parts of the lower coils lying on arcs of greater radius than that of the upper coils, so that the lower part of said branches of the channel lies on the surface of an imaginary cone passing through the conductor parts of the upper and lower coils, substantially as described.

4. In an electrical induction furnace, a magnetic yoke, a furnace having a channel for the melting bath, and two conductor coils embracing the opposite sides of the yoke, each of said coils having a flattened portion passing between the sides of the yoke to provide room in the same plane for the other coil without overlapping therewith; substantially as described.

5. In an electrical induction furnace, a magnetic yoke, a furnace having a channel for the melting bath, and. two conducting coils embracing the opposite sides of the yoke, each of said coils having a flattened portion passing between the sides of the yoke to provide room in the same .lane for the other coil without overlapping t ierewith and having a remaining portion extending substantially around three-quarters of a circle; substantially as described.

In testimony that I claim the foregoing as my invention, I have signed my name in presence of two subscribing witnesses.

KARL ALBERT FREDRIK HlOR'lH. 

